The present invention relates to an apparatus and method for transferring a volume of fluid and, in particular, to an adapter for connecting a pipetter to a hypodermic needle.
It is known to use a pipetter to transfer precise volumes of fluid from one object to another object. The pipetter is fitted with a plastic disposable pipetter tip for containing the volume of fluid to be transferred. The pipetter tip prevents the pipetter from becoming contaminated with the fluid to be transferred. However, pipetter tips are relatively large in size compared to hypodermic needles and do not have the sharp ends or structural strength of hypodermic needles. Therefore, the known arrangement of a pipetter with a pipetter tip is not suitable for transferring fluids when only a very small opening is available for insertion of the pipetter tip or when a surface must be pierced in order to transfer the fluid.
When the features of a hypodermic needle are required, that is, when only a very small opening is available for insertion or a surface must be pierced in order to transfer the fluid, the known solution is to use a hypodermic needle attached to a syringe. The hypodermic needle typically includes a holder which is secured to the end of a syringe. One problem with the use of syringes and hypodermic needles is that volumes cannot be measured as accurately with a syringe as with a pipetter. For example, with a syringe, the volume is measured by visually aligning the meniscus of the fluid in the syringe tube with the desired volumetric mark placed on the tube. On the other hand, pipetters have, for example, a rotary threaded adjustment wherein the volume is digitally shown as a function of the movement of the rotary knob.
Another problem with the syringe and needle apparatus is that the fluid to be transferred actually enters the body of the syringe. Therefore, after each use, the syringe must either be sterilized or thrown away. Even though disposable plastic syringes are available, their cost becomes very great when performing hundreds of transferring operations daily, as in a modern research laboratory.
Another problem with syringes and needles is that the needles are typically threaded on and off the syringe. The threading operation creates a risk of the needle piercing the hand of the user. The risk is especially great if the needle is contaminated with a toxic substance or life form.